illativePronunciation: /ɪˈleɪtɪv/Definition of illative adjective 1of the nature of or stating an inference. proceeding by inference. 2 Grammar relating to or denoting a case of nouns in some languages used to express motion into something. noun the illative case, or a word in this case. Derivatives illatively adverb Origin: late 16th century: from Latin illativus, from illat- 'brought in' (see illation)illative in other Oxford dictionaries Definition of illative in the US English dictionary